The case against an Australian IT worker who allegedly killed a Muslim grandfather with a wine bottle lobbed from a Singapore high-rise has worsened, after prosecutors declared his actions were "religiously motivated".

Melbourne man Andrew Gosling is accused of throwing a wine bottle 15-metres from his seventh-floor apartment balcony in August, fatally striking the head of a 73-year-old granddad of nine in a public barbecue area two floors below.

Fresh documents tendered in a Singapore court on December 5 allege Mr Gosling also injured a woman with the wine bottle he threw, and that the act was "religiously aggravated".

Andrew Gosling, 47, has been charged over the death of a grandfather in Singapore. (9News)

For a crime to be "religiously aggravated", an offender must demonstrate hostility towards the victim immediately before or after committing the offence, based on the victim's religion, local media reports. The offence could also be motivated by hostility towards members of a racial or religious group based on their membership of that group.

Mr Gosling has been detained in a Singapore jail since surrendering to police on August 28, 10 days after Nasiari Sunee died in hospital.

He was initially charged with causing death by rash act, and faced a maximum five-year sentence.

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Under Section 74 of the Penal Code, if convicted of causing hurt by a weapon in a religiously aggravated act, a court can impose a punishment one-and-a-half times more than the sentence for the offence.

Mr Nasiari was visiting the 35-storey Spottiswoode 18 condominium on August 18 to celebrate a relative's housewarming. He was about to eat dinner when the bottle allegedly flew down from an upper floor.

His family heard a thud, and turned to see Mr Nasiari collapsed in the building's public barbecue area. His head was bleeding and the wine bottle lay intact beside his body. The 73-year-old died in hospital the next day.

The additional charges brought against Mr Gosling on December 5 stated the bottle also struck a woman named Ms Manisah who was at the table, causing bruises to her right shoulder.

Singapore police went door-to-door inside the Spottiswoode 18 condominium. They had a photo of the wine bottle, a 2016 Polissena Il Boro, and were requesting fingerprints from residents.

Mr Gosling had only been in Singapore two months after taking up a contract with Australian multinational mining company Orica.

Nasiari Sunee, pictured with members of his family, died after he was struck on the head with a wine bottle just before eating dinner with family and friends. (9News)The 35-storey Spottiswoode 18 condominium; Nasiari Sunee, pictured with his wife, died after being hit in the head with a wine bottle allegedly thrown from the high-rise's 7th floor. (Ronny Chin & Associates / Supplied)

The defence lawyer for Mr Gosling, Gloria James, told nine.com.au in an earlier statement that said many Singapore locals were angry at her client.

Ms James said she met Mr Gosling in her law firm's offices twice before the Australian IT specialist had handed himself in to police.

"He was clearly distraught and was suffering. He trembled and shook as he spoke. He was also in tears as he did not expect his act to cause the death of someone."